Should the y-axis always go to 0? Is the answer different for line charts and bar charts?
A newly published article by at @Meta_Psy by @JessiWittPhD collected empirical evidence about y-axis scaling in #dataviz #datavis. https://open.lnu.se/index.php/metapsychology/article/view/895/2084
1/">https://open.lnu.se/index.php...
A newly published article by at @Meta_Psy by @JessiWittPhD collected empirical evidence about y-axis scaling in #dataviz #datavis. https://open.lnu.se/index.php/metapsychology/article/view/895/2084
1/">https://open.lnu.se/index.php...
A common belief is that bar charts communicate more accurately if the y-axis goes to zero but that y-axes can be cropped for line charts. 2/
This article suggest that both assumptions are wrong⊠or at least incomplete. The experiments asked subjects to report an effect size (difference over standard deviation) between two values displayed as bars or a line and with different y-axis scales. 3/
The results showed that for a y-axis with a wide range (âfullâ condition), people reported a smaller effect size. When the y-axis had a narrow range (âminimalâ condition), people reported a larger effect size. Different responses despite showing the same data. 4/
And this bias was present no matter what graph type was used. Bar chart. Line chart. Error bars. No error bars. Always a response bias⊠despite effect size not even making sense without error bars! 5/
So when estimating the difference and variance between aggregated values, people can be biased in either direction by the scale of the y-axis. 6/
Meta-Psychology requires open practices for all submissions.
Data and materials: https://osf.io/hw2ac
Reviews">https://osf.io/hw2ac&quo... and decision letters: https://osf.io/hxk2u ">https://osf.io/hxk2u&quo...
All reviewers (including me!) are named in the decision letters and in the header of the article for accountability. 7/
Data and materials: https://osf.io/hw2ac
Reviews">https://osf.io/hw2ac&quo... and decision letters: https://osf.io/hxk2u ">https://osf.io/hxk2u&quo...
All reviewers (including me!) are named in the decision letters and in the header of the article for accountability. 7/
Last, but not least, this articleâs analyses underwent a reproducibility check by @tobiasmueh. So reported results were recomputed and verified. 8/8